Clamping device for porcelain shells



July 7, 1942. E. E. ARNOLD ET A.. 2,289,164

Y CLAMPING DEVICE FOR PORCELAIN SHELLS Filednc. 15, 1959 WITNESSES:

WM Edwm EAmozd (s.

Patented July 7, 1942 j CLAMPING DEVICE FOR PORCELAIN SHELLS Edwin E. Arnold, Pittsburgh, Pa., and John H.

Chiles, Jr., Sharon, Pa., assignors to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsyl- Vania Application December 13, 1939, Serial No. 309,038

3 Claims.

Our invention relates to means for clamping a ceramic body to another body and particularly to means for clamping a porcelain shell such as used in the electric insulator .art to a base, :a cap or an adjacent porcelain.

The means for accomplishing this as taught by the prior art comprise securing a fiange to the porcelain and bolting the flange to the piece to which the porcelain is to be clamped. This method presents serious disadvantages. place the diiference in the coeicient of eXpansion of the ange metal and porcelain will highly stress the porcelain shell and may cause it to rupture. In addition, the heavy ila-nge section when drawn down may place undue stress on the porcelain due to the leverage action of the ange.

lt is, accordingly, an object of our invention to provide new and improved means for clamping a `cera-mic body to another body.

Another object of our invention is to provide means for clamping a porcelain shell to another body in such a manner that no excessive stress is put upon the porcelain shell or its connection with the clamping means.

It is a further object of our invention to `provide a gasket arrangement and a clamping means for securing a porcelain shell to another body in such manner that a predetermined pressure may be exerted upon the gasket Without the porcelain shell being subjected to any excessive or unbal xanced stress.

Other objects of our invention Will become evident from the following detailed description, taken in lconjunction with the accompanying drawing in which:

Figure 1 isa view partly in section of a means taught by the prior art for connecting a porcelain shell to a metal member.

Fig. 2 is a view in section of a portion of a connection made in accordance with a preferred form of our invention.

Fig. 3 is an enlarged view in section showing the gasket of Fig. 2 in stressed condition; and,

Figs. 4, 5, 6, 'l and 8 are views in section of portions of connections made in accordance with modifications of our invention.

Throughout the drawing corresponding parts are designated by the same numerals followed by different alphabetic characters. In the prior art construction shown in Fig. l, the porcelain shell l is seated on the annular gasket 2 disposed on the base 3 which may be a portion of a housing for electrical apparatus. The gasket 2 extends across only a portion of the thickness of the shell I while a gasket stop 4 of non-compressible Ina- In the first terial is provided to limit the compression thereof'. .An annular metallic flange 5 is attached to the shell l by cement 6 4and secured to the base 3 by bolts 7. It will readily appear that With this construction that the porcelain and cement at the upper portion of the flange 5 as at A will be subjected to considerable tensile stress `while the lower portions thereof will be under compression at B.

Another disadvantage of this prior art :construction lies in the fact that when the gasket 2 is first compressed, all the pressure is concentrated on the `porcelain surface in Contact therewith. After the porcelain contacts the stop 4 the pressure across the face will change, and, depending on how tightly the porcelain is drawn down, it may become excessive over the stop area.

In the embodiment of our invention shown in Fig. 2 a porcelain shell designated by 8 has a metallic flange 9 secured thereto by cement I. At a plurality of points, the flange 9 is tapped at an an-gle with the vertical as at Il and screw threaded to receive bolts I2 extending through the annulus I3, the inner periphery of which fits against the annular shoulder i4 of the base member I5. The annulus I3 is lpreferably of two-piece spring construction and bent to form a partly conical outer portion at IB to provide flat seats for the heads of the bolts I2. An annular groove I1 of somewhat greater width than the thickness of the shell 8 is provided in the base I5 and a gasket IS which may be of a deformable out not necessarily com-pressible material is seated therein to receive the edge of the shell 8. An auxiliary groove I9 may be formed within the groove II to further control the sealing characteristics of the gasket I8.

It will become obvious that an effect of .applying the force in an angular direction in the preferred embodiment of Fig. 2 is to eliminate the undesirable turning moment produced in the prior art construction of Fig. l.

The gasket I8 being of full width will result in the pressure upon the shell 8 being evenly distributed and it may be maintained at a constant predetermined value since the annulus I3 has spring characteristics. Similar results may be obtained with a rigid annulus if the heads of the bolts are seated thereagainst through other suitable means hereinafter described, such as helical springs.

The groove I'I, in addition, supports the gasket against sidewise displacement and the rounded edges of the shell 8 prevent stress concentration at the boundary zones of contact with the gasket I8. The auxiliary grooving l!) provides means for regulating the effective gasket area and, in fact, such grooving may be useful where a main groove l'l is not provided. This action of the gasket I8 will be more readily understood from Fig. 3 which is a View of the gasket arrangement of Fig. 2 when under compression. The same members are indicated by the same numerals in the two Ygures.

In the modification of our invention shown in Fig. 4, the shell 8a, has a metallic band 2'9 on which is formed a projecting portion 2l cemented thereto as at 22. An annular iiange member 23 is attached to the base member 24 by bolts AV25 and engages the projecting portion 21 of the band 20 to maintain the shell Ba in position. A spring 2S is provided between the head of each bolt 25 and the base 24 to provide a predetermined i'lXed pressure between the shell Ba and the gasket 18a which is shown in compressed condition. The spring may be placed at the other end of the bolt 25 or one may be employed at each end if desired. Preferably a softening gasket 27 is provided between the projecting portion 2| and the ange member 23. The gasket IBa and the structure cooperating therewith is similar to that shown in Figs. 2 and 3.

In this structure of Fig. 4, the flange does not exert the leverage action o-f the prior art structure of Fig. 1. In addition to the length of the lever arm being considerably reduced, it is possible to vary the shape of band 2o and the position of the projecting portion 2| so as to grade the tension and compression effects at the ends of the cemented portion 22.

The construction of Fig. differs from Fig. 3 in that the porcelain shell 8b is attached to the base through a pair of annular members 2e and 29 drawn together by means of bolts 25h. The upper member 28 which preferably comprises two spring portions contacts the projecting portion 2 IIJ` of the band 20h through softening gasket 2lb while the lower annulus 2S also has spring characteristics and seats at its inner periphery against a shoulder Mb in the base leb. It will be obvious that the desired spring pressure may be obtained by making only one of the annular members 28 and 29 of spring construction. In fact, springs such as shown in Fig. 4 as well as any other suitable spring arrangement may be employed to obtain a predetermined pressure on the gasket even where annuli 28 and 2e do not have spring properties.

The embodiment of our invention shown in Fig. 6 differs from that of Fig. 5 in that no metal band is required since the porcelain shell 8c carries a flanged portion 39 integral therewith. A gasket 3| is employed on the portion sii at its surface of contact with the annular member 22o forming with the annular spring member 29o and bolts 25e an assembly'similar to that shown in Fig. 5.

In Fig. '7 an annular spring member 2M seats against the shoulder 14d and supports one end of each of the `bolts 25d. The remainder of this assembly is similar to that of Fig. 4.

The modiiicationshown in Fig. '8 comprises a porcelain shell 8e carrying a band 2de cemented thereto as at 22e. A ring member Si) carries a flange 34 which acts against the upper surface of band 28e through a gasket 21e. A two piece spring annulus `29e 'ts against'the shoulder le and 'carries bolts v25e which engage in `screwthreaded holes 32 in ring 33. The construction and arrangement of the gasket 18e is the same as in the other forms shown. It will be noted that in this modification there is no lever action within the structure comprising the shell 8e, ring 22e and cement 22e.

The use of annular members such as 29 (Fig. 5) engaging the base member is of particular advantage in those cases where the base is of ceramic or other non-metallic material which may lack the strength required to support the bolt directly.

Although we have shown and described certain specific embodiments of our invention, We are fully aware that many modifications thereof are possible. The invention therefore is not to be restricted except insofar as is necessitated by the prior art and by the spirit of the appended claims.

We claim as our invention:

l. An assembly comprising a ceramic shell, a base member having a continuous groove of substantially the same shape as, but wider than, the edge of said shell and having a second narrower continuous groove at the bottom of said first groove spaced from the edges thereof, resilient gasket means disposed in said first groove in a position bridging said second groove and with said shell seated thereon, projecting means carried by said body, and means including a spring member engaging said projecting means for resiliently clamping said shell to said base member.

2. An assembly comprising a ceramic shell, a base member, resilient gasket means disposed between an edge'of said shell and said base member, said gasket means -being of a width substanw tially equal to that of said edge of said shell, said base member having a groove extending over a portion only of the width of its contact surface with said gasket means so as normally to be bridged thereby, annular projection means disposed on the exterior of said shell, annular shoulder means on said base member, a pair of annular plate members, the inner edge of one of said annular members engaging a surface of said projection meansopposite said base member and the other of said annular members engaging said shoulder means, at least one of said annular members having spring characteristics, and `radially spaced means for clamping said annular members together at the outer edges thereof to secure said shell and base member together in a resilient manner.

3. An assembly comprising -a ceramic shell, a base member, resilient gasket means disposed between an edge of said shell and said base member, said gasket means being of a width substantially equal to that of said shell, said base member having at its Contact surface with said gasket a continuous groove which is of narrower width than said gasket and is normally bridged thereby, a metallic band secured to said shell, means cn said band for gripping a plurality of radially spaced bolt members disposed at an angle with the axis thereof, bolts secured in said gripping means, an annular shoulder portion on said base member, and an annular resilient plate member with its inner edge in engagement with said shoulder portion and its outer edge in engagement with said bolts to -secure said shell and said base member together in a resilient manner.

EDWIN ARNOLD. JOHN H. CHILES, JR. 

